The M. D. Anderson Cancer Center in Houston, Texas predicts that cancer will become the leading cause of death in the United States by the year 2002. Cancer presently results in over one thousand five hundred deaths every day in the United States (550,000 deaths every year). Therapy modalities for cancer are plentiful and continued to be researched with vigor. Still, the preferred treatment continues to be physical removal of the cancer. When applicable, surgical removal is preferred (breast, colon, brain, lung, kidney, etc.). Open, excisional, surgical removal is often extremely invasive so that efforts to remove cancerous tissue in less invasive ways continue, but have not yet been perfected.
The only cure for cancer continues to be the early diagnosis and subsequent early treatment. As cancer therapies continue at earlier stages of diagnosis, the cancerous tissue being operated on is also smaller. Early removal of the smaller cancers demand new techniques for removal and obliteration of these less invasive cancers.
There are a variety of techniques that attempt to accomplish less invasive cancer therapy, but so far without sufficiently improved results. For example, the ABBI system from U.S. Surgical Corporation and the Site Select system from Imagine Corporation, attempt to accomplish less invasive cancer therapy. However, conventional techniques require more than Minimally Invasive Surgery (MIS) techniques in that they require a large core (that is more than about 15 mm diameter) incision. Additionally, the Mammotome system from Johnson and Johnson and MIBB system from U.S. Surgical Corporation also require large core (over about 4 mm diameter) access to accomplish biopsy.
A recent convention held by the American Society of Surgical Oncologists on Mar. 13, 2000 reported that conventional stereotactic core biopsy (SCB) procedures fall short in providing definitive answers to detail precise surgical regimens after this SCB type vacuum assisted biopsy, especially with ductile carcinoma in situ (DCIS). Apparently these percutaneous systems damage xe2x80x9cnormalxe2x80x9d tissue cells so that it is difficult to determine if the cells are xe2x80x9cnormal damagedxe2x80x9d cells or early pre-cancerous (e.g. Atypical Ductal Hyerplasi (ADH)) cells.
A study presented by Dr. Ollila et al. from the University of North Carolina, Chapel Hill, demonstrated that histology and pathology is compromised using these conventional techniques because of the damage done to the removed tissue specimens. Hence, for many reasons, including the fact that DCIS is becoming more detectable and hence more prevalent in breast cancer diagnosis in the U.S., there is a growing need to improve upon conventional vacuum assisted core biopsy systems.
Broadly, the present invention is directed to procedures, including biopsy and tumorectomy methods, and associated apparatus which provide for less invasive techniques while also providing for enhanced tissue specimens being retrieved.
A first aspect of the invention is directed to a tissue removal method in which a tissue separation device is positioned at a target site within a patient. A tissue sample is separated by the movement of tissue separation element through the tissue at the target site. A factor relating to the restriction of the passage of the tissue separation element through the tissue is monitored so that energy supplied to the tissue separation element can be adjusted. The procedure may be carried out percutaneously. The method may include radially expanding one or more heated, wire-type tissue separation elements and then rotating the support shaft. The factor being monitored may include, for example, strain on the tissue separation element, the rotational force supplied to the device, the pressure exerted against the tissue by the tissue separation element, etc. Monitoring may also be done manually with tactile feedback to the user.
A related aspect of the invention is directed to a tissue removal assembly in which an elongate tissue separation device comprises a tissue separation element mounted to a support. The tissue separation element is movable from a retracted state to an extended state. A tissue separation element driver is operably coupled to the tissue separation element to permit the tissue separation element to separate a target tissue mass from a patient. The tissue separation element driver comprises an energy source coupled to the tissue separation device. A sensor is operably coupled to at least one of the tissue separation device and the tissue separation element driver and senses resistance to the separation of the target tissue mass from the patient. A feedback device operably couples the sensor and the tissue separation element driver so that the amount of energy supplied can be adjusted based on the resistance to the passage of the tissue separation element through the patient""s tissue.
Certain advantages accrue through the use of the above-described tissue removal method and assembly. An appropriate amount of energy can be supplied to the tissue separation element so that when, for example, the tissue separation element is a wire which extends radially outwardly to form an arch passing through the target tissue, the wire can be heated so to cauterize the tissue it passes through as it moves from the radically retracted state to the radically extended state; this helps to prevent spreading of viable cancer tissue into non-cancerous tissue regions. Heating or otherwise energizing the tissue separation element with RF energy, vibrational or other mechanical energy, etc., may also reduce the force required to move the tissue separation element through tissue mass, especially when passing through dense or fibrotic tissue or a variation in densities. Once the tissue separation element has been fully extended, it may or may not need to be heated or otherwise energized to pass through non-diseased tissue surrounding the suspect tissue mass. Therefore, undesirable damage to healthy tissue may be minimized and the spread of cancerous tissue to non-cancerous tissue may be effectively eliminated.
A further aspect of the invention is directed to a method for helping to prevent seeding of a tissue tract including positioning a protective device along the tissue tract and then moving tissue from the target site, through an opening in the protective device and into an inner region of the protective device. The tissue is then moved along the tissue tract and out of the patient while keeping the tissue within the device. The protective device may be maintained substantially in place along the tissue tract as the tissue is moved out of the patient.
Another aspect of the invention is directed to percutaneous tissue mass retrieval assembly comprising a shaft, a radially expandable blocking element at the distal end of the shaft, a suspect tissue mass enveloping device movable from an enlarged, tissue mass-surrounding state to a contracted, tissue mass-constricting state so to enable the tissue mass to be removed from a target site with a reduced lateral size.
A still further aspect of the invention is directed to a method for maintaining access to a void within a patient by placing an access sleeve along a tissue tract connecting an access site in the patient""s skin and a void in the patient. This method may take place, for example, following the removal of a biopsy specimen, the removal creating the void. The method may also take place following removal of an entire suspect tissue mass as well. This method ensures convenient and accurate re-access to the void when, for example, an additional tissue sample is needed, therapeutic drugs are to be delivered to the void, a prosthesis is to be implanted, etc.
An additional aspect of the invention is directed to a method for removal of target material from a target site and includes percutaneously placing an expandable blocking element at a first position distal of the target material, expanding the expandable blocking element, percutaneously placing a removing element at a second position, at least substantially surrounding the target material with the blocking element and the removing element, and then removing the blocking element, the removing element and the target material therewith from the patient along a tissue tract connecting the target site with an access site in the patient""s skin. The expandable blocking element may be a radially expandable, tubular mesh material. The removing element may include a tubular mesh element having a radially expandable, open distal end. One or both of the removing element and blocking element may be at least partially radially collapsed prior to removing the blocking element, removing element and target material therewith from the patient. This method helps to ensure target material is properly captured and permits it to be removed percutaneously; the removal may be preceded by radially collapsing the blocking and/or removing elements to help reduce the size of the device passing through the access site in the patient""s skin.
A still further aspect of the invention relates to a target material removing device including a shaft, first and second axially spaced-apart, radially expandable elements carried by a distal portion of the shaft. The expandable elements are remotely selectively movable between radially retracted and radially expanded states so that the expandable elements can be used to bracket target material to permit the target material to be removed from the patient along with the device. This device permits a surgeon to easily and accurately locate the target material, which is often very difficult to visually differentiate from surrounding tissue, by locating the expandable elements. The radially expandable elements are preferably sufficiently hard so as to be detectable by palpation.
A still another aspect to the invention is directed to a method for locating a target mass within a patient comprising extending the distal end of a shaft to a position distal of a target mass, positioning first and second radially expanding bracketing elements at positions distal of and proximal of the target mass, moving the bracketing elements from radially retracted states to radially expanded states thereby bracketing the target mass, and locating a target mass using the bracketing elements. The bracketing elements, when radially expanded, may define a bracketed region therebetween sized to completely contain the target mass. The target mass may be located by palpation of the bracketing elements or with the aid of a surgical incision at least partially exposing at least one of the bracketing elements.
An additional aspect to the invention is directed to a method for maintaining percutaneous access to an excisional site comprising positioning first and second locational elements within a patient at a target site, the locational elements carried by elongate elements extending from the locational elements along a tissue tract and out through an access site in the patient""s skin. The first elongate element and first locational element therewith are then removed from the patient and the target site is accessed using the second elongate element and second locational element therewith. The second or both the first and second locational elements may be radially expandable locational elements. This aspect of the invention provides the surgeon the ability to accurately locate the target site. It also permits one of the locational elements to be removed and one to be left at the target site.
A still additional aspect of the invention is directed to a percutaneous access assembly including first and second separately movable locational devices, each device including a shaft and a radially expandable element mounted to the shaft. The radially expandable elements are locatable adjacent to one another.
Other features and advantages of the invention will appear from the following description in which the preferred embodiments and methods have been set forth in detail in conjunction with the accompanying drawings.